GAGES: A stream gage database for evaluating natural and altered flow conditions in the conterminous United States

Abstract

Stream flow is a controlling element in the ecology of rivers and streams. Knowledge of the natural flow regime facilitates the assessment of whether specific hydrologic attributes have been altered by humans in a particular stream and the establishment of specific goals for stream‐flow restoration. Because most streams are ungaged or have been altered by human influences, characterizing the natural flow regime is often only possible by estimating flow characteristics based on nearby stream gages of reference quality, i.e., gaged locations that are least disturbed by human influences. The ability to evaluate natural stream flow, that which is not altered by human activities, would be enhanced by the existence of a nationally consistent and up‐to‐date database of gages in relatively undisturbed watersheds. As part of a national effort to characterize stream‐flow effects on ecological condition, data for 6785 U.S. Geological Survey (USGS) stream gages and their upstream watersheds were compiled. The sites comprise all USGS stream gages in the conterminous United States with at least 20 years of complete‐year flow record from 1950–2007, and for which watershed boundaries could reliably be delineated (median size = 578 km2). Several hundred watershed and site characteristics were calculated or compiled from national data sources, including environmental features (e.g., climate, geology, soils, topography) and anthropogenic influences (e.g., land use, roads, presence of dams, or canals). In addition, watersheds were assessed for their reference quality within nine broad regions for use in studies intended to characterize stream flows under conditions minimally influenced by human activities. Three primary criteria were used to assess reference quality: (1) a quantitative index of anthropogenic modification within the watershed based on GIS‐derived variables, (2) visual inspection of every stream gage and drainage basin from recent high‐resolution imagery and topographic maps, and (3) information about man‐made influences from USGS Annual Water Data Reports. From the set of 6785 sites, we identified 1512 as reference‐quality stream gages. All data derived for these watersheds as well as the reference condition evaluation are provided as an online data set termed GAGES (geospatial attributes of gages for evaluating stream flow).

Historical Changes in Fish Assemblage Structure in Midwestern Nonwadeable Rivers

“…(Table 1). Average precipitation varies 87.5-90.3 cm among basins (Falcone et al, 2010). Although the surficial geology varies within and among river basins, soil texture is similar and includes coarse sandy-loams in the upstream reaches to fine siltyloams in the downstream reaches of each river [National Hydrography Dataset (NHD); U.S. Geological Survey; I.S.…”

“…Numerous landscape and instream alterations have occurred in our study rivers over the past 150 y; however, the majority of these changes could only be quantified since the 1950s (Table 1; Falcone et al, 2010). During Iowa's initial settlement in the 1850s, the landscape was composed of about 69% prairie, 19% forest, and 12% wetlands (Zohrer, 2006;Gallant et al, 2011).…”

“…During Iowa's initial settlement in the 1850s, the landscape was composed of about 69% prairie, 19% forest, and 12% wetlands (Zohrer, 2006;Gallant et al, 2011). According to recent research by Falcone et al (2010), 75-80% of the original land cover has been transformed for agricultural land use (i.e., row crop and pasture) and 6-9% of the land cover was transformed for urban land use among basins (Table 1). Agriculture and urban land cover compose 20-45% and 7-11% of mainstem riparian areas, respectively.…”

Rising air and stream-water temperatures in Chesapeake Bay region, USA

“…Physical characteristics of the landscape that could influence WT trends for each watershed were extracted from the Geospatial Attributes of Gages for Evaluating Streamflow Version II dataset (GAGESII; http://water.usgs.gov/GIS/metadata/usgswrd/XML/gagesII_Sept2011.xml, accessed 18 June 2013), an update to Falcone et al (2010). Landscape factors extracted included 190 measures of location, topography, hydrology, soils, land cover, dams, and population density.…”

Reference hydrologic networks I. The status and potential future directions of national reference hydrologic networks for detecting trends

“…In a related development, however, the USGS has recently completed a quantitative analysis of gauged drainage basins to establish reference basins in the conterminous United States (Falcone et al 2010), primarily for determining natural streamflows relevant to aquatic ecosystems and for evaluating natural versus altered flow conditions. The resulting database, referred to as GAGES (Geospatial Attributes of Gages for Evaluating Streamflow), incorporates basin attributes for 9324 USGS streamflow gauges and their upstream drainage basins that have completeyear flow records from 1950 to 2009.…”